It has long been a problem in the steel industry to prevent and/or inhibit rusting of steel products, particular sheet such as is used in the appliance and container industries.
A common commercial treatment now employs dioctyl sebacate, such as is suggested in U.S. Pat. No. 2,884,338. Typically, a composition of dioctyl sebacate (DOS) is applied to a sheet such as container stock moving at high rates of speed. See the Smith and Bray U.S. Pat. No. 3,826,675 examples wherein a corrosion protection composition is deposited electrostatically at 1000 feet per minute. For treatments of container stock generally, the reader may also be interested in Allen U.S. Pat. Nos. 2,579,777 and 2,579,778 showing the use of tributyl citrate as the lubricant for container stock. See also U.S. Pat. Nos. 2,784,104; 2,790,778; 3,121,016 and 2,790,779.
Sodium benzoate is a known corrosion inhibitor also, but has been extremely difficult to apply, without the presence of water, to steel surfaces and has proven to cause problems in lacquer adhesion during the later stages of container production. It has other advantages in addition to corrosion inhibiting, however, such as being non-toxic, flavor-free, non-irritating, colorless, and odorless. The prior use of sodium benzoate as a corrosion inhibitor for steel in the form of a coating is discussed, among other places, in the April 1962 issue of Modern Packaging in an article by J. R. Hutchins and R. T. Knies.
In U.S. Pat. No. 3,121,016 the authors suggest the use of combinations of oleoyl N-methyl glycine with petroleum oil and sodium sulfonated petroleum oil.
The authors of U.S. Pat. No. 3,314,968 suggest the use as corrosion inhibitors of compositions similar to N-methyl glycine, namely, certain salts of naphthenoyl sarcosines, which can be made by reacting naphthenoyl chloride with sodium sarcosinate; barium naphthenoyl sarcosinate is used as a corrosion inhibitor in small amounts in an oil carrier, in examples VII and VIII.
We are aware of the recent use of combinations of DOS and certain alkyl sarcosines, specifically N-oleoyl sarcosine, as lubricating and corrosion inhibiting coatings for steel sheet. However, difficulties have been encountered in the use of these compositions. Specifically, in order to obtain adequate protection, it has been necessary to apply unnecessarily thick coatings, which is not only wasteful and expensive, but which results in significant capillary migrations after coiling or stacking. Obviously, any significant capillary migrations completely reverse whatever success has been achieved toward the end of even, uniform, continuous, and eyehole-free coatings. Such capillary migrations result in a phenomenon known as puddling, an erratic and highly undesirable characteristic for further use of the steel product.
We are not aware, however, of any composition proposed or used in the prior art which contains the same components as ours or which employs them to achieve the excellent corrosion inhibiting results which we obtain.